Exercise device



FIG. 1 is a top view of an exercise device showing my new design;

FIG. 2 is a perspective side view thereof;

FIG. 3 is a second perspective side view thereof; and,

FIG. 4 is an end view thereof.

The broken line showing of stitching illustrates portions of the exercise device and forms no part of the claimed design. 

The ornamental design for an exercise device, as shown and described. 